On Saturday at the World Science Festival, microbiologists David Relman, Jo Handelsman, Rob Knight, and Martin Blaser convened for a discussion on how the microbiome relates to our health. Our microbiome, the collective bacteria, viruses, fungi and other microorganisms that live in the digestive tract, allows us to digest food properly and fight off disease. Research suggests that an unhappy microbiome may contribute to autoimmune diseases, allergies, depression, and even Alzheimer’s.